Conditional Spatial Join?

Question

I need to join two layers (a fishnet grid and land cover). I'd like the join to occur only if the the land cover occupies 50% or more of each fishnet grid (See image below).

Can anybody provide an example or point me in the right direction?

More details: Ideally I only need the grids to be created that contain 50% or more of the land cover layer.

Answer 1

You can do this in a few steps:

edit: As Ali pointed out, you do need your grid to be polygons, not lines for this workflow.

• Create a field on the grids to hold the area of each grid (or since they are the same in this case, just note what that area is)
• Intersect the grids and land usage layers.
• Compare the area of each output polygon from the intersect to the area of the grid and exclude any that aren't 50%. I.E:
  • Select all features where (SHAPE_AREA / GRID_AREA) >= 0.5
  • Export those selected features into a new feature class
• Join the filtered land use attributes back to the grids.
  • You could use Join Field, joining on the FIDs output by the intersect tool or,
  • Spatial Join the exported selection from above to the original grid. Just be sure to use CONTAINS and not INTERSECTS.